Unconventional Resources - Field Labs
Hydraulic Fracturing Test Site (HFTS) Last Reviewed
May 2018

DE-FE0024292

Goal
This project is to conduct a field-based hydraulic fracturing research program for horizontal shale wells with the objectives of reducing and minimizing potential environmental impacts, demonstrating safe and reliable operations, and improving the efficiency of hydraulic fracturing. The research will advance our understanding of the hydraulic fracturing process in shale reservoirs, and thus, enable the design and execution of effective fracture stages that significantly contribute to production. Improved design and execution of fracture stages will also reduce the number of future infill wells drilled, and reduce water volume and energy input. A smaller environment footprint associated with shale drilling will be the result of this work.

Performer
Gas Technology Institute, Des Plaines, IL 60018

Background
Despite the long history of hydraulic fracturing, the optimal number of fracturing stages during multi-stage fracture stimulation in horizontal wells is not known. In addition to the increased expense of multistage fracturing in horizontal wells,  increasing the number of fracturing stages does not always correlate with an increase in production. The problem is the application of a uniform fracture stimulation design to all stages with no consideration for geological variations along the wellbore. The result is an inefficient use and costly waste of energy and water.  

Optimization of the fracturing process requires an understanding of the cause-and-effect relationship between fracturing parameters and local geological properties at a given location along the wellbore.  Realizing that the generalized rock mechanics theories and hypotheses are not truly applicable to fractured and laminated shales, quantifiable impacts of a shale’s geomechanical and depositional features are a prerequisite for design and implementation of optimized hydraulic fractures. The overarching goal of this project is to understand and define the relationships of shale geology and fracture dynamics using detailed field data that includes coring of the fracture domain. Analyses of the data will aid in updating fracture design models, and improve the effectiveness of individual hydraulic fracture stages.

Impact
In conventional fracture stimulation, a selected fracture design is implemented at all fracture stages of a horizontal well without consideration for reservoir heterogeneity or dynamic stress changes that occur during fracturing. As a result, 50 percent of the total production from the well will come from about one-third of the fracture stages pumped.  The intended fracturing optimization through the HFTS program aims to eliminate this inefficiency by creating effective fractures at every stage. The net effect of such efficiency improvement will increase production from the well with no increase in the amount of water, chemicals, proppants, and energy required. This translates to minimized air emissions and other environmental impacts associated with production of a unit volume of oil and gas.  

Accomplishments (most recent listed first)
Laredo Petroleum offered a field site for the project in August 2015. The Laredo site includes 11 horizontal wells (10,000’ horizontal legs) drilled through the Upper and Middle Wolfcamp formation in the Permian Basin. In addition, Laredo has vertical wells nearby which are being used as observation wells. Significant events and field activities completed to date include:

  • Two open-hole logs in horizontal laterals (Image + Quad Combo)
  • Vertical pilot hole drilled through Wolfcamp formation.
    • Quad combo log run
    • Image log run
    • 57 rotary side wall cores recovered
    • 50 core vault side wall cores recovered
    • Diagnostic fracture injections tests conducted
  • Cross-well seismic surveys completed between three wells on test site prior to and post-hydraulic fracturing operations.
  • Toe diagnostic fracture injections tests were conducted in multiple wells.
  • Website established to share data between project partners.
  • Water and air samples collected prior to, during, and post-hydraulic fracturing operations.
  • 400+ fracture stages completed in the 11 wells.
  • Radioactive and chemical tracers used in stimulations.
  • Colored proppant markers used in two wells close to the slant core well to be drilled.
  • Microseismic monitoring conducted during fracture treatments.
  • Core planning workshops held to design slant core well and de-risk operations.
  • Slant Core Well drilled at 81 degrees through stimulated rock volume.
  • 595 feet of core recovered from Slant Core Well (437 feet of continuous core in the Upper Wolfcamp and 158 feet of continuous core in the Middle Wolfcamp).
  • Pressure gauges have been installed in slant core well to monitor pressure during production.
  • Core description has been completed by multiple teams, and results have been incorporated into a final core description report.
    • Two main sets of natural opening-mode fractures filled with calcite cement were identified trending broadly NE-SW and WNW-ESE.
    • A total of 11 faults were identified, all within the Upper Wolfcamp formation.
    • More than 700 total fractures (natural and induced) were identified in the core.
  • Fracture modeling is ongoing.
  • Completed analysis of sludge collected from core barrels. Results provide a detailed subsurface proppant distribution every three feet for the entire cored interval. Proppant size and concentration was quantified as well as the amount of natural fracture cements, providing an indication of natural fractures.
  • Proppant scraped from fractures of core is being analyzed to detect proppant quantity and color.
  • Final microseismic processing has been completed for each fracture stage.
  • A core viewing workshop was held with all participants to showcase fractures and features in entire 595’ feet of core.
  • Completed multiple-pad systematic pressure interference test on all 11 test wells.
  • A second sequential pressure interference test across 13 wells has been completed.
  • Slabbed entire slant core.
  • 3D Laser scanned all hydraulic fratcures and many natural fractures before slabbing core.

Current Status (May 2018)
The core has been slabbed and photographed (white and UV light). The remaining work on the slant core includes a full geologic description. Samples collected from individual core fractures continue to be analyzed at BEG to determine concentration and size distribution of proppant. The following field data continues to be collected: bottomhole pressure and temperature data in producing and slant core wells, production data. Data analysis and integration continues, with fracture proppant results and results of the geologic core description remaining to integrate/correlate. Core samples are being collected and will be distributed to the National Labs for ongoing DOE research.

The consortium is currently preparing for the upcoming URTeC conference, where 13 technical papers summarizing specific results will be presented in a special session dedicated to HFTS.

Laredo Petroleum and GTI have agreed to perform an EOR field pilot near the original HFTS. The field pilot will involve injecting natural gas into a previously fracture stimulated well in an attempt to produce additional oil. The field pilot will utilize cyclic gas injection, where natural gas is injected into the reservoir below fracturing pressure but above oil miscibility pressure. After a sufficient amount of gas is pumped, pumping is stopped and the gas is allowed to soak in the reservoir and dissolve in the oil. After some time, the well is placed back on production, and the dissolved gas helps to drive out additional oil. This process is then repeated many times until it becomes un-economic to continue with additional injection-soak-production cycles. This process is commonly known as the huff-and-puff method. Experiment details and timing are being finalized with HFTS consortium. The experiment is valued at about $35 million.

Project Start: October 1, 2014
Project End: June 30, 2018

DOE Contribution: $7,613,075
Performer Contribution: $14,653,014

Contact Information
NETL – Gary Covatch (gary.covatch@netl.doe.gov or 304-285-4589)
GTI-Jordan Ciezobka (jordan.ciezobka@gastechnology.org or 847-768-0924)

Additional Information:

NETL-Backed Field Testing Project Seeks to Improve Efficiency and Safety of Hydraulic Fracturing (Dec 2017)
With a long record of success advancing hydraulic fracturing innovations, NETL teamed with Gas Technology Institute (GTI) of Des Plaines, Ill., to develop and execute a hydraulic fracturing test site program to answer questions, advance the understanding of the hydraulic fracturing processes to attain greater efficiencies, and improve environmental impacts.

Hydraulic Fracturing Test Sites (Aug 2017)
Presented by Jordan Ciezobka, Gas Technology Institute, 2017 Carbon Storage and Oil and Natural Gas Technologies Review Meeting, Pittsburgh, PA

Hydraulic Fracturing Test Sites (Aug 2016)
Presented by Jordan Ciezobka, Institute of Gas Technology, 2016 Carbon Storage and Oil and Natural Gas Technologies Review Meeting, Pittsburgh, PA